They have ceramics 300x300 , half the walls are tiled and he's taking off the tiles , he fancies himself as a diyer, all 4 walls are solid walls, i reckon im going to have to do a lip as they wont pay extra for boarding they are really tight on the monies i.e they want a good job done for a half decent price, thats the vibe i was getting
The weight ratio for 300x300mm tiles would allow you to use a cement 'bagged' adhesive which will let you use a deeper notched trowel and if you take off the skim plaster in the solid walls for the border tile you should have the millimetres you requre.